Inferior quality optical media, such as CD-ROM discs or other discs, have been found to be susceptible to hairline cracks located toward the inner diameter. Under high rotation speeds, inferior media or media with hairline cracks can fracture after some time.
For example, referring to FIG. 1, a CD-ROM disc 1 will have hairline cracks 2 if used under wear-and-tear conditions for some time. Such hairline cracks may also often be found on those discs manufactured by an unlicensed manufacturer. Furthermore, referring to FIG. 2, the firmness of the locking feature 10 found on the cases 12 for CD-ROM discs prohibits convenient removal of the discs. When a user pulls a disc out of a case, the disc is forced against the locking feature. This causes the disc to bend and gives rise to hairline cracks 2 at the inner diameter 3 of the disc. Furthermore, these hairline cracks can continue to propagate as playing continues, eventually resulting in fracture of the disc.
Referring to FIG. 3, a drive 20 is shown with the tray 22 and tray cover (shutter) 24 in an open position. When a disc within the drive is spinning at high speeds (e.g., in excess of 8000 r.p.m.) and fractures, the front plastic enclosure 26 typically seen on drives is often insufficient to prevent disc fragments from flying out. This is because the front plastic enclosure simply is not as strong as the metal top enclosure 28. Consequently, these projectiles pose a considerable danger to the user and any people proximate the drive. Furthermore, the tray can be displaced outwardly from the assembly and the tray cover can become dislodged and cracked.
Attempts to lock the tray 22 in a closed position have proven to be inadequate because heavy impact forces can still open the tray. Furthermore, attempts to redesign the plastic tray cover 24 by creating thicker sections and strengthening features have failed because the tray can still be forced outwardly by high impact forces. Moreover, since sharp projectiles can penetrate the front plastic enclosure, the utilization of a stronger material has been employed. Nevertheless, it is possible that fragments can get caught between the front plastic enclosure and the metal top enclosure 28.